Power management in portable communication devices is an ever-present issue now being further exacerbated by the popular introduction and use of larger color displays with white LED backlights. User talk times are significantly affected because most of these large color displays remain on during phone calls. Existing phones fail to take advantage of some patterns exhibited by handset users as a means to reduce current drain. A typical user averaging a three (3) minute phone call will perceive a noticeable reduction in talk time due to the fact that both a backlight and a display remain on while the call is active. Some phones also include backlit keypads that remain illuminated as well during an active call.
Portable phones generally keep their display on at all times during a call while the backlight is typically turned off after 30 seconds of no key-activity (user selectable). The 30 seconds that the backlight remains on combined with a display that is not turned off during a phone call substantially affects the talk times based on the actual usage pattern. In some phones, this method may not be sufficiently efficient enough because it may leave the backlight turned on (using 40–60 mA) up to a significant percentage of each phone call time. With displays and illumination mechanisms in portable communication products increasingly vying for additional power from a portable battery, existing methods fail to provide adequate talk and standby times demanded by consumers.